The present invention relates to a method, composition and device for removing dissolved oxygen from solutions containing alcohols and/or acids. The dissolved oxygen is removed from these solutions for the purposes of retarding oxidation deterioration, rancidity, gum formation, etc.
Ethyl alcohol, or ethanol (CH.sub.3 CH.sub.2 OH), is the basis for the very large and prosperous alcoholic beverage industry which offers a wide range of products varying in alcohol content from less than one percent to greater than sixty percent. In addition, ethyl alcohol, is also utilized industrially as an intermediate reagent in numerous processes for the production of chemicals etc., and is used extensively in solvents, antiseptics, anti-freezing compounds, and fuels.
In this regard, specifically denatured alcohols (i.e. ethyl alcohol containing added denaturants such as methyl alcohol, pyridine, benzene, kerosene, mixtures of primary and secondary aliphatic higher alcohols etc.) have many uses including use in food extracts, toiletries, pharmaceuticals, and cleaning products. As an industrial solvent, it is reported that ethyl alcohol is second to only water, and is a critical raw material in the manufacture of drugs, plastics, lacquers, polishes, plasticizers, perfumes etc.
Moreover, ethyl alcohol, either alone or in combination with a wide variety of petroleum products, may be burned as a fuel. Mixtures of ethyl alcohol blended with various petroleum distillates are frequently referred to by the term "gasohol".
Ethyl alcohol may be produced either synthetically from ethylene (i.e., by either the direct or indirect hydration of ethylene) or by the natural fermentation of sugars, starches or cellulose. While natural fermentation is still the principal means for producing the alcoholic content found in beverages and food products, the synthetic process is the method most frequently used in the production of ethyl alcohol for commercial use.
In the natural fermentation of ethyl alcohol, the ethanol may be derived from any material which contains sugar. In this regard, the sugar present in the raw material can be converted directly to ethyl alcohol, or if the sugar is contained in the raw material in more complex forms (such as starches or cellulose), the complex forms must first be converted to simple sugars by hydrolysis, etc. The sugars are then fermented by enzymes from yeast etc. to produce the ethyl alcohol.
An example of the production of ethyl alcohol from complex forms of sugar is the alcoholic fermentation of starchy raw materials in beer production. More particularly, beer is generally defined as an alcoholic beverage made by the fermentation of starchy materials such as barley, along with other brewing ingredients such as corn, rice, wheat or oats. The starchy materials are broken down by enzymes (i.e. hydrolyzed) during the malting process to produce less complex water soluble compounds such as sugars and short chained peptides. The sugars are then fermented to produce the alcoholic content of the beer, which varies greatly depending upon the critical ingredients and processes utilized.
Along this line, most beers have an ethyl alcohol content of between 2-6 weight percent. In addition, the alcoholic fermentation reaction also yields minor by-products such as glycol, higher alcohols (fusel oil comprising a mixture of n-propyl, n-butyl, isobutyl, amyl and isoamyl alcohols) and traces of acetaldehyde, acetic acid and lactic acid. These minor by-products are generally produced in almost all types of alcoholic fermentation reactions.
An example of the production of ethyl alcohol from simpler forms of sugars is the natural fermentation process which occurs in wine production. Although the production of wine is generally associated with the fermentation of sugar from the juices of grapes, juices from other fruits and plant material such as rice etc. may be utilized. The alcoholic content in wine varies greatly from less than 5 weight percent to greater than 18 percent.
Although beer, wine and other alcoholic beverages and food products are somewhat immune to microbial spoilage as a result of their ethyl alcohol content and/or low pH, oxidation deterioration still occurs. In this regard, it is well known that the presence of oxygen in products, including products containing ethyl alcohol and/or acids, can cause a great deal of detrimental damage. For example, carbonated and non-carbonated beverages and food products having low pH's and/or containing ethyl alcohol such as fruit juices, soft drinks, beer, wine, jams, jellies, and preserves, pie fillings, salad dressings, pickles, relishes, and other condiments, olives, sauerkraut, soups, vegetable juices, and pastes, etc. may be unstable over even a relatively short period of time due to undesirable changes produced by oxidative deterioration. Among the oxidative changes which beverages and food products incur over time include changes in color, consistency, and flavor. Since these changes in the beverages and food products greatly decrease the product's marketability, it is desirable to reduce the presence of oxygen in the overall product.
In addition, it is also quite desirous to remove oxygen from various commercial products having low pH's and/or contain ethyl alcohol. This is particularly true in a number of chemical products, wherein the presence of oxygen can create undesirable by-products. For example, in pharmaceutical products, it is often quite beneficial to remove oxygen to avoid contamination, formation of intermediate free radicals, etc.
Furthermore, it is also advantageous to remove oxygen from low pH and/or ethyl alcohol containing products which are stored for relatively long periods of time in order to maintain the packaging of the product. For example, if oxygen is present in the beverage and/or food product, the oxygen included in the product can also cause deterioration of the container's plastic or metal lining, packaging etc. Thus, in modern beverage and food product preparation systems, it is desirable to remove the extraneous oxygen from the fluids to greatly increase the shelf life of the packaged product.
This is particularly important in modern brewing operations, wherein the feed stock must be almost completely deoxygenated in that the presence of even a small fraction of oxygen can result in an unacceptable product. As a result, in modern beverage and food product operations, various deoxygenating devices including vacuum systems, oxygen-purging apparatuses, etc. are used to extract the oxygen.
However, vacuum dereators and gas flushing apparatuses are fairly expensive and they do not necessarily reduce the dissolve oxygen content to an acceptable level. Furthermore, these apparatuses have some drawbacks in that the oils and lubricants used therein sometimes find their way into the fluids being treated. The inclusion of even a small amount of such harmful agents within the beverage and/or food product can produce undesirable color and/or flavor changes in the overall product, as well as toxic effects.
In addition, in order to remove some of the oxygen which slips by the vacuum dearators and/or the gas-flushing apparatuses, it is sometimes desirable to add various chemical antioxidants to the product for the purposes of retarding oxidation and associated deterioration. However, a number of chemical antioxidants useful in industrial products such as plastics and polishes, are not suited for food products because of their toxicity. Moreover, the consuming public is becoming increasingly more concerned about the uses of chemicals and preservatives in foods and beverages including antioxidants. Thus, a great deal of research is currently being undertaken to develop not only more universal, but also safer, antioxidants.
Chemical antioxidants are inorganic or organic compounds added to various materials for the purposes of retarding oxidation and associated deterioration. They may be utilized alone or in combination with deoxygenating processes such as those indicated above. It is thought that some of the chemical antioxidants operate by binding with specific intermediate free radicals (i.e. peroxy radicals) produced during oxidation degradation. By binding with the intermediate free radicals, the free radicals are incapable of propagating the chain reaction to decompose into other harmful free radicals. As a result, by binding with the intermediate reactant, antioxidants effectively inhibit the oxidation degradation reaction. A more detailed explanation concerning the operating mechanism of antioxidants may be found in Van Nostrand Reinhold Encyclopedia of Chemistry. Fourth Edition, 1984.
The use of antioxidants in foods, pharmaceuticals, and animal feeds, as direct additives is closely regulated because of their potential toxicity. Along this line, when used in foods, chemical antioxidants are regulated to extremely low percentages by the Food and Drug Administration (FDA). Although antioxidants have been utilized for several decades and occur naturally in some food substances, intensive research continues in order to develop universal non-toxic antioxidants.
In this regard, the desirable properties of antioxidants, particularly when used in food products, may be summarized as indicated by Van Nostrand Reinhold, supra, by the following characteristics: (1) effectiveness at low concentrations; (2) compatibility with the substrate; (3) non-toxicity to consumers; (4) stability in terms of conditions encountered in processing and storage, including temperature, radiation, pH, etc.; (5) non-volatility and non-extractability under the conditions of use; (6) ease and safety in handling; (7) freedom from off-flavors, off-odors, and off-colors that might be imparted to the food products; and (8) cost effectiveness. As a result, antioxidants vary greatly depending upon such factors as the composition of the substrates, pH, temperature, processing conditions, impurities etc.
An example of a common chemical antioxidant currently being utilized in products containing alcohols and/or acids is the use of sulfur dioxide gas (SO.sub.2) and its related sulfite salts (i.e. sodium sulfite, potassium metabisulfite etc.) Sulfur dioxide gas and its sulfite salts are widely used for preserving fruits and fruit juices, alcoholic beverages produced from fruit juices, vegetables and vegetable juices, syrups, concentrates, purees etc. In addition, sulfur dioxide and its sulfite salts also extend the storage life of raw fruit and vegetables by preventing the enzymatic "browning" reactions associated with oxidative degradation.
The effectiveness of sulfur dioxide gas and its sulfite salts varies considerably depending upon the concentration and pH conditions of the product desired to be protected. The preferred operating pH range of sulfur dioxide and its sulfite salts for preventing oxidation and inhibiting microbial degradation appears to be about a pH of 2.5-3.5.
As a result of this effective pH range, sulfur dioxide and its sulfite salts are used extensively in the production and storage of wine. The sulfites are used not only for sanitizing equipment etc., but also for inhibiting the growth of any natural microbial flora present on the fruit prior to fermentation. This is done prior to the addition of pure cultures of the appropriate wine making yeast to prevent growth and competition of undesirable organisms. During fermentation, the sulfites act not only as an antioxidant but also as a clarifier and dissolving agent. Furthermore, sulfur dioxide and its sulfite salts are often used after fermentation and during storage to prevent oxidation degradation and/or undesirable postfermentation alterations by various microorganisms. The levels of sulfur dioxide and its sulfite salts present in wine during storage varies greatly depending upon the condition of the fruit, temperature, pH, sugar concentrations etc. but is normally in the range from about 20 to about 70 ppm.
Although the use of sulfur dioxide and other chemical antioxidants has proven to be quite beneficial for controlling oxidative degradation of various products, including those products containing alcohols and/or acids, a number of serious undesirable side effects can also be produced. This can be particularly demonstrated in regard to the use of sulfur dioxide and/or sodium sulfite as a chemical antioxidant in wine, fruit juices etc. wherein a portion of the public is allergic and/or hypersensitive to the sulfites utilized. Hence, it would be desirous to produce a safe, non-toxic substance which continuously removes oxygen from food products and chemical substances containing alcohols and/or acids without producing any harmful side effects to the end products or user.
Accordingly, the present invention is directed to a method, composition and device for continuously removing oxygen from solutions containing alcohols and/or acids in a safe and efficient manner. The method and composition of the present invention may be utilized as an antioxidant in industrial solutions containing acids and/or alcohols such as plastics, polishes etc., as well as beverages and food products, without altering the desired properties of the products produced thereby. The method and composition of the invention fulfill the desired properties of an effective antioxidant as indicated above.